Prague, 5 December 2003 (RFE/RL) -- At least 40 people were killed and dozens injured today when a blast ripped through a passenger train in Russia's southern Stavropol Krai, not far from the breakaway republic of Chechnya.

Russian authorities say the explosion was caused by a bomb and that a criminal investigation for terrorism and premeditated murder has been opened.

Nikolai Patrushev, the director of the Federal Security Services (FSB), today reported personally to President Vladimir Putin about the investigation. He said preliminary findings show the bombing was carried out by a group of at least four attackers.

"We can already state that this group was made of three women. Two women were in the carriage and jumped off the train just before the explosion. Another woman was obviously charged with directing the blast. She is among the victims and will probably not survive. There was also a man whose identity we have not been able to determine yet. We've found remains of his body [in the wreckage] and discovered hand grenades attached to his legs. This one was probably the suicide bomber," Patrushev said.

Russia's state television quotes security officials as saying the perpetrators of the attack might have boarded the train somewhere between the cities of Kislovodsk and Yessentuki.

Deputy Prosecutor-General Sergei Fridinskii, who was urgently dispatched to the scene, suggested that Chechen guerrillas are behind the attack. "What we have seen and what we have discovered at the site of the incident testifies to a similarity with other terrorist attacks," he said. "Among other things, remnants of explosives we have found indicate the blast could have been triggered by a 'sehit' [a Muslim martyr]."

In a statement released after the explosion, the Foreign Ministry of the separatist government of Chechnya declined any responsibility for the blast and reiterated its condemnation of terrorist attacks against civilians.

The explosion occurred shortly before 8 a.m. while the crammed Kislovodsk-Mineralne Vody commuter train was approaching the town of Yessentuki. The train's second carriage was sliced in two, and a fire broke out in the wreckage.

Most of the victims were killed on the spot. Four people died of their wounds in regional hospitals. Rescuers and investigators were still trying to identify bodies by mid-afternoon. One eyewitness interviewed by RFE/RL's North Caucasus Service said at that hour of the day, the train was usually carrying many college students. "Among passengers were mainly youth, students who were going to school early in the morning," the witness said.

General Viktor Kazantsev, the presidential envoy to the Southern Federal district, arrived in Yessentuki shortly after the attack with a joint investigation team of the Interior Ministry and the FSB.

Russian news agencies say security measures have been beefed up in Mineralne Vody and other regional spas.

This is the second attack on the Kislovodsk-Mineralne Vody line in recent weeks. In early September, twin blasts tore through a train near Pyatigorsk, killing four passengers and injuring 40 others.

Stavropol Krai lies north of Chechnya, where independence fighters have been battling Russian troops since 1994. A string of bombings blamed on radical Chechen guerrillas has struck the Northern Caucasus region in the past few months -- contradicting Putin's claims that the situation in the restive republic is returning to normal. The Yessentuki blast took place just two days before Russia's parliamentary elections, which are expected to increase Putin's power base.

Yurii Volkov, who runs the campaign staff of the pro-Putin Unified Russia party, told the ITAR-TASS news agency the attack was aimed at disrupting the 7 December election in the Northern Caucasus region. Putin today made a similar statement. "The crime that was committed today is without doubt an attempt at destabilizing the situation in the country on the eve of the parliamentary elections," Putin siad.

Russian state television today quotes Interior Ministry and FSB officials as saying two cars filled with explosives and weapons were found overnight in the town of Karabulak. Two women and two men were arrested in connection with the discovery.